[R] Lines in a line graph not visible when values are identical
Bob Green
bgreen @end|ng |rom dy@on@br|@net@org@@u
Mon Oct 12 10:58:06 CEST 2026
Thanks. I opted to change the linestyle, lty in
Base R or linetype in ggplot2. It worked fine.
At 06:44 PM 10/10/2026, CALUM POLWART wrote:
>I'm not entirely sure I've understood the issue,
>but is this exactly what jitter exists for
>
>
>geom_line(position=position_jitter(w=0.1) ...
>
>Adding some slight "bounce" to the plotted likes to make them not overlap.Â
>
>Jitter always worries me slightly that you are
>lying slightly with the data although the idea
>is it is supposed to be by a neglible amount.
>
>Or, using a dotted line over a solid line can fix this ?
>
>In essence if you have
>
>---------Â
>
>Currently with both lines under eachother making
>one of them dotted means you get
>
>--•---•---•-
>
>The [poor] colour vision world might suggest that's better anyway!
>
>Or I may have misunderstood the problem!
>
>On Thu, 8 Oct 2026, 22:03 Bob Green via R-help,
><<mailto:r-help using r-project.org>r-help using r-project.org> wrote:
>Thanks Rui,
>
>Much appreciated. Regarding why I spelt out
>millimetres, I seldom use them as a measurement
>so it was mostly for that reason and because the
>data was in an Excel spreadsheet.
>
>To get a more direct comparison, I create a panel
>of four bargraphs, one for each parameter by year.
>
>Regards
>
>Bob
>
>Â At 01:27 AM 10/9/2026, Rui Barradas wrote:
> >Hello,
> >
> >What if instead of colors, you facet the plot by Year?
> >
> >
> >ggplot(DF, aes(x = Parameter, y = Millimetres, group = Year)) +
> >Â Â geom_line(linewidth = 1) +
> >Â Â geom_point(size = 2) +
> >Â Â labs(
> >Â Â Â title = "Parameters by Year",
> >Â Â Â x = "Parameter",
> >Â Â Â y = "Millimetres ($)"
> >Â Â ) +
> >Â Â facet_wrap(~ Year) +
> >Â Â theme_minimal()
> >
> >
> >Also, the data in dput format.
> >
> >DF <-
> >structure(list(Parameter = structure(c(1L, 2L, 3L, 4L, 1L, 2L,
> >3L, 4L, 1L, 2L, 3L, 4L, 1L, 2L, 3L, 4L, 1L, 2L, 3L, 4L, 1L, 2L,
> >3L, 4L, 1L, 2L, 3L, 4L, 1L, 2L, 3L, 4L), levels = c("Tail", "Tail_b",
> >"Nose_b", "Nose"), class = "factor"), Millimetres = c(0, 0, 20.3,
> >74.9, 0, 0, 14, 63.7, 11.2, 2.8, 16.3, 72.6, 0, 0, 17.1, 72.5,
> >11.3, 2.9, 16.9, 74.7, 28.1, 4.9, 6.8, 37.7, 25.9, 5.2, 11.2,
> >68.1, 30.2, 6.35, 15.1, 76.2), Year = c("2010-2012", "2010-2012",
> >"2010-2012", "2010-2012", "2014", "2014", "2014", "2014", "2016",
> >"2016", "2016", "2016", "2023", "2023", "2023", "2023", "2024",
> >"2024", "2024", "2024", "2025C", "2025C", "2025C", "2025C", "2025B",
> >"2025B", "2025B", "2025B", "2026", "2026",
> >"2026", "2026")), row.names = c("1",
> >"2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12", "13",
> >"14", "15", "16", "17", "18", "19", "20", "21", "22", "23", "24",
> >"25", "26", "27", "28", "29", "30", "31", "32"), class = "data.frame")
> >
> >Bob Green via R-help
> <<mailto:r-help using r-project.org>r-help using r-project.org> escreveu (quinta,
> >8/10/2026 Ã (s) 11:19):
> > >
> > > Hello,
> > >
> > > I'm pretty rusty using R but wanted to compare
> > > four parameters measured in mm, in terms of
> the year an object was created.
> > >
> > > My problem is that where there are identical
> > > values, only one line is produced. For example,
> > > for the first parameter "tail",only five of a
> > possible eight lines are visible.
> > >
> > > The code and full dataset are below. I considered
> > > making trivial differences to identical values of
> > > a parameter to create difference,but no doubt
> > > there are more elegant or sophisticated options.
> > >
> > > Any advice is appreciated,
> > >
> > > Bob
> > >
> > > library(ggplot2)
> > > library(tidyr)
> > > library(readxl)
> > > DF <- read_excel("C:/Files/DataLong.xlsx")
> > > DF
> > >
> > >
> > > DF$Parameter <- factor(DF$Parameter, levels =
> > > c("Tail", "Tail_b", "Noseb", "Nose"))
> > >
> > >
> > > ggplot(DF, aes(x = Parameter, y =
> > Millimetres, color = Year, group = Year)) +
> > >Â Â geom_line(linewidth = 1) +
> > >Â Â geom_point(size = 2) + labs(title =
> > > "Parameters by Year", x = "Parameter", y = "Millimetres ($)") +
> > >Â Â theme_minimal()
> > >
> > > ##Data
> > >
> > >
> > > # A tibble: 32 × 3
> > >Â Â Â Parameter Millimetres Year
> > >Â Â Â <fct>Â Â Â Â Â Â <dbl> <chr>
> > >  1 Tail       0  2010-2012
> > >  2 Tail_b      0  2010-2012
> > >  3 Nose_b     20.3 2010-2012
> > >  4 Nose      74.9 2010-2012
> > >  5 Tail       0  2014
> > >  6 Tail_b      0  2014
> > >  7 Nose_b     14  2014
> > >  8 Nose      63.7 2014
> > >  9 Tail      11.2 2016
> > > 10 Tail_b      2.8 2016
> > > 11 Nose_b     16.3 2016
> > > 12 Nose      72.6 2016
> > > 13 Tail       0  2023
> > > 14 Tail_b      0  2023
> > > 15 Nose_b     17.1 2023
> > > 16 Nose      72.5 2023
> > > 17 Tail      11.3 2024
> > > 18 Tail_b      2.9 2024
> > > 19 Nose_b     16.9 2024
> > > 20 Nose      74.7 2024
> > > 21 Tail      28.1 2025C
> > > 22 Tail_b      4.9 2025C
> > > 23 Nose_b      6.8 2025C
> > > 24 Nose      37.7 2025C
> > > 25 Tail      25.9 2025B
> > > 26 Tail_b      5.2 2025B
> > > 27 Nose_b     11.2 2025B
> > > 28 Nose      68.1 2025B
> > > 29 Tail      30.2 2026
> > > 30 Tail_b      6.35 2026
> > > 31 Nose_b     15.1 2026
> > > 32 Nose      76.2 2026
> > >
> > > ______________________________________________
> > >
> <mailto:R-help using r-project.org>R-help using r-project.or
> g mailing list -- To UNSUBSCRIBE and more, see
> > >
> <https://stat.ethz.ch/mailman/listinfo/r-help>https://stat.ethz.ch/mailman/listinfo/r-help
> > > PLEASE do read the posting guide
> >
> <https://www.R-project.org/posting-guide.html>https://www.R-project.org/posting-guide.html
> > > and provide commented, minimal, self-contained, reproducible code.
>
>______________________________________________
><mailto:R-help using r-project.org>R-help using r-project.org
>mailing list -- To UNSUBSCRIBE and more, see
><https://stat.ethz.ch/mailman/listinfo/r-help>https://stat.ethz.ch/mailman/listinfo/r-help
>PLEASE do read the posting guide
><https://www.R-project.org/posting-guide.html>https://www.R-project.org/posting-guide.html
>and provide commented, minimal, self-contained, reproducible code.
More information about the R-help
mailing list